Influenza activity in the United States remained elevated through February 2, 2019, and is expected to continue for several more weeks. Influenza vaccination is the best way to reduce the risk of influenza and its potentially serious consequences, including hospitalizations in adults and deaths in children. Influenza antiviral medications are an important adjunct to vaccination in the treatment and prevention of influenza. Since December 2018, influenza activity increased overall and remained elevated through early February. Nationwide, influenza A(H1N1)pdm09 viruses have predominated, but in the southeastern United States influenza A(H3N2) viruses have predominated. As of February 2, 2019, this has been a low-severity influenza season, with a lower percentage of outpatient visits for influenza-like illness (ILI), lower rates of hospitalization, and fewer deaths attributed to pneumonia and influenza compared with recent seasons. Nevertheless, this season has resulted in many illnesses, hospitalizations and deaths, which are being reported in-season for the first time. The majority of the influenza viruses characterized antigenically and genetically are similar to the cell-grown reference viruses representing the 2018–19 Northern Hemisphere influenza vaccine viruses.

While flu vaccines vary in how well they work, vaccination can provide important protection against influenza. People age 6 months and older who have not yet been vaccinated this season should be vaccinated. People who are at high risk of serious flu complications and develop flu symptoms, and people who are very sick with flu should be treated early with antiviral medications. CDC recommends yearly influenza vaccination for children at least 6 months old and adults. Early estimates indicate that influenza vaccines have reduced the risk of medically attended influenza-related illness by almost half (47%) in vaccinated people so far this season. Vaccination reduced the rate of illness caused by the predominant influenza H1N1 virus by about 46 percent among patients of all ages, and by about 62 percent among children 6 months through 17 years of age. Vaccination provided similar protection to that seen in previous H1N1 seasons in children and in adults younger than age 50. For these estimates, 3,254 children and adults with acute respiratory illness were enrolled from November 23, 2018 to February 2, 2019 at five study sites with outpatient medical facilities in the United States.

When indicated, opioid analgesic prescription durations of seven days or less appear sufficient for most individuals with acute pain conditions treated in primary care settings. Among 176,607 patients with a primary care visit associated with an acute pain complaint in 2014, 7.6 percent filled an opioid analgesic prescription with a median of four to seven days’ supply across 10 conditions. The probability of refill was less than 25 percent for 9 of 10 conditions when patients initially filled a seven-day supply of opioid analgesic. These results suggest that seven days or less of opioid analgesic might be sufficient for most but not all patients treated in primary care settings for acute pain. Treatment strategies for acute pain with opioid analgesics, if clinically appropriate, should account for patient and condition-specific characteristics, which may reduce or extend the need for opioid analgesic therapy.

A new CDC analysis shows that use of methamphetamine more than doubled among heterosexual men and women diagnosed with syphilis between 2013 and 2017. A new CDC analysis finds that substance use—including methamphetamine and injection drugs – more than doubled among heterosexuals with syphilis from 2013-2017. Once nearly eliminated in the U.S., syphilis has increased dramatically in recent years, including among reproductive-aged women and newborn babies. To better understand this recent trend, researchers analyzed self-reported risk behaviors among heterosexual women and men, and among gay and bisexual men who were diagnosed with primary and secondary syphilis. The findings indicate that two major public health issues — increasing syphilis and increasing substance use among heterosexuals — are intersecting epidemics. To address these challenges, it is important that programs to prevent and treat sexually transmitted diseases and substance-use disorders be aware of these findings and integrate prevention and treatment services when possible.

Combining data from public-health interviews and molecular sequencing creates a powerful new tool for understanding communities experiencing HIV transmission and for identifying population- or individual-level interventions to reduce HIV transmission and improve health outcomes. Identifying named partners through public health interviews is an important strategy for interrupting HIV transmission. Analyzing HIV molecular sequence data can also identify networks of potential transmission partners. Among named partner linkages where both people had an HIV sequence available, 33.8 percent also had a molecular linkage and were deemed plausible transmission partners. Supplementing named partner data with molecular data might detect HIV transmission networks not elucidated through traditional public health interviews and identify opportunities for prevention in rapidly growing clusters of HIV infections.

The Advisory Committee on Immunization Practices now recommends routine hepatitis A (HepA) vaccination for all people ages 1 year and older who experience homelessness. In October 2018, the Advisory Committee on Immunization Practices (ACIP) unanimously approved updating the recommendations for HepA vaccine to include all people ages 1 year and older experiencing homelessness. The new recommendation is based on evidence showing the substantial public health and cost benefit of routine HepA vaccination for people who are homeless. Additionally, recent outbreaks of hepatitis A virus transmission have demonstrated the vulnerability of this population to this infection. Between 2016 and 2018, more than 7,000 cases of hepatitis A infection were reported in 12 states. The majority of these infections were among people reporting homelessness and/or injection or non-injection drug use. HepA vaccination for people who are homeless will protect these vulnerable individuals and reduce the risk of person-to-person outbreaks among this population.

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